In a 5G system, a base station transmits a synchronization signal block on an initial access sub-band in a large bandwidth. For example, a synchronization signal block is transmitted on a sub-band with a bandwith of 5 MHz within a system bandwidth of 100 MHz. A first Control Resource Set (CORESET) is transmitted on a first sub-band of the large bandwidth, and a second CORESET is transmitted on a second sub-band of the large bandwidth. By a Physical Downlink Control Channel (PDCCH) in the first CORESET or the second CORESET, the base station schedules a User Equipment (UE) to receive common control messages on an indicated Physical Downlink Shared channel (PDSCH) to acquire Remaining Minimum System Information (RMSI) or paging messages.
Scheduling information in the PDCCH includes information of resource allocation, so as to inform the UE on which Resource Blocks (RBs) to receive the PDSCH.
However, in an idle state, the base station may not need to indicate a system bandwidth to the UE, thus the UE cannot know the system bandwidth of the base station. The base station cannot know bandwidth capability of the UE in the idle state as well as different UEs have different bandwidth capabilities. As the system bandwidth of a single carrier in a 5G system increases significantly, in the idle state, existing resource allocation methods cannot adapt to the 5G system currently due to low resource allocation efficiency.